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Tekna Offshore Pumps 2007

Pump Theory API Reciprocating Displacement Pumps.

Steve Digby SPX Process Equipment Limited Bran+Luebbe Operation U.K.

SPX Process Equipment

2003 2002

WCB-Flow Products

GD Engineering

2005 Plan Employees 2585

OFM

Oilfield Fabricating & Machine

After Market & Field Services

Pump Theory API Reciprocating Displacement Pumps

Topics

· · · · · Reciprocating versus Rotary Pumps Basic Operation of Reciprocating Pumps API Specifications 674 & 675 Suction Side Installation Considerations Overall Cost of Ownership

Pump Theory API Reciprocating Displacement Pumps

· API stands for American Petroleum Institute · API 674 and 675 are widely used as an industrial standard for reciprocating displacement pumps. · Mainly used in Petroleum, Chemical Processing, and Oil&Gas Industry. · Describes and specifies constructional design, qualification criteria, and how pumps and documentation shall be executed.

Pump Theory API Reciprocating Displacement Pumps

Reciprocating metering/dosing pumps deliver a controlled & accurate flow to predetermined points of a process independent of pressure.

Pump Theory API Reciprocating Displacement Pumps

API 675 Metering Pump With Diaphragm Pumphead

API 674 Reciprocating Triplex Pump With Diaphragm Pumpheads

Pump Theory API Reciprocating Displacement Pumps

Metering Pump Equation

V=A.h.n

V = theoretical Volumetric flow of the metering pump A = plunger square area h = stroke length n = stroking speed (stroke frequency)

Positive Displacement Pumps Reciprocating

Definition (in accordance with API Standard 674) There is no actual definition in the standard other than highlighting the difference between a Power Pump & Direct Acting Pump. Essentially these pumps transmit a predetermined mass flow at medium to high pressure. Pumps are normally configured in Triplex, Quintuplex and Septuplex designs.

Positive Displacement Pumps Controlled Volume

Definition (in accordance with API Standard 675) "A controlled volume pump is a reciprocating pump in which precise volume control is provided by varying effective stroke length". · Such pumps are also known as metering, proportioning, chemical injection, dosing, or controlled volume pump. · These pumps deliver a controlled & accurate flow to predetermined points of a process independent of pressure.

Pump Theory API Reciprocating Displacement Pumps Typical Deviations to API 675

API Listing 1.5 Equipment offered is referring to German and European standards i.e. DIN, EN, IEC, ISO,.... 2.2.5.1 Details of threading conform to ISO. 2.12.3 Unless proposed differently visual indication of capacity setting is shown as actual stroke length. 2.13.1.13 Bolts are calculated and selected in accordance with German pressure vessel code (AD-Merkblätter). 3.1.7 Motors are flanged directly to the pump. Consequently, there is no need for jackscrews. 3.3 Metering pumps are suitable for mounting directly onto prepared concrete. Base plates are therefore optional and can be quoted at additional cost. 3.3.9 If not stated differently base plates will not be furnished with jackscrews. 3.4.3.2 If not stated differently single point terminal box for instrumentation is not included. 3.4.4.3 The gauges used for local diaphragm rupture indication have dials either 63 mm or 100 mm, depending on size of pumphead. 3.4.5 Electrical systems are not included unless expressly required and specifically quoted.

Pump Theory API Reciprocating Displacement Pumps API Data Sheet ­ Purchaser Information

1 2 3 4 5 6 7 For: No. of motors required 1 Site Serial no. TBA Remarks Notes: O indicates information to be completed by Purchaser. indicates information to be completed by manufacturer. API standard 674 governs unless otherwise noted OPERATING CONDITIONS (to be completed by purchaser) 8 9 10 11 12 13 14 15 Liquid (HC) Condensate Pumping temperature (°C) PT: Normal 19 Maximum 58 Minimum -9 Density @ PT (kg/m³): 569,8 Vapor pressure @ PT (bar): Viscosity @ PT (cP): 0,16 Acceleration head (m) Note 1 NPSH available (m): 14,7 Capacity @ PT (m³/h): Maximum Note 2 Minimum Note 3 5,3 Rated Discharge pressure (bar g): Maximum Minimum Rated Note 4 Suction pressure ( bar g): Maximum Minimum Rated 17,8 Differential pressure (bar g): Maximum 19,2 Minimum Rated 16,2

Pump Theory API Reciprocating Displacement Pumps

Installation Considerations & How to Avoid Problems

Pump Theory API Reciprocating Displacement Pumps Flow Pattern of various Pumps Types

Simplex Pump Duplex Pump Triplex Pump Centrifugal Pump

Pump Theory API Reciprocating Displacement Pumps

What we are Trying to Avoid Suction Side · Insufficent NPSHA · Pump Starvation · Cavitation Discharge Side · Insufficent Flow · Over Pressure · Pipe Hammer

General Poor Pump Operation In almost all cases of insufficient flow rate or frequent service calls the pump will be blamed, not the system Only Recognised as Problems During Commissioning or Initial Operation.

Pump Theory API Reciprocating Displacement Pumps

Many Installations Are Designed On Smooth Flow Conditions & Ignore Factors Such as:· Reciprocating Pumps Generate a Pulsating Flow · ~3x Equivalent Smooth Flow. · Line Losses Can be High. · Crucial on Critical Applications i.e. Liquid Gases, High Temperature, Volatile Liquids.

Pump Theory API Reciprocating Displacement Pumps Flow Pattern of a Single Head Pump

100 % Capacity setting 60 % Capacity setting Top dead Center

Discharge

Bottom dead Center Suction

Bottom dead Center

Pump Theory API Reciprocating Displacement Pumps

Two Major Factors That Can Adversely Affect The Operation of Reciprocating Pumps Buy Are Often Overlooked are: ·Friction Losses

Higher Viscosity Applications Pressure Required to ensure that the liquid flows continually in the system during the maximum demanded flow volume. Low Viscosity Application

·Mass Acceleration Losses

Pressure Required to cause the liquid to move at the beginning of each plunger stroke ·Both Have a high impact on NPSHA . ·Only the higher of the two values is considered. ·On reciprocating pumps this is generally Mass Acceleration.

Pump Theory API Reciprocating Displacement Pumps

Factors Affecting Mass Acceleration Pressure · Plunger or Piston Diameter. · Stroke Length · Internal Pipe Diameter & Overall Length. · Pump Speed. · Pump Configuration (Single or Multi Head) Example.

Single Head Pump 20mm Dia Plunger x 20 mm Stroke Length Operating Speed 100 Strokes/Min Fitted To 8mm NB Pipe Mass Acceleration Pressure = 0.84 m/m Pipe Length = 10m P = 8.4m or 0.84 Bar

Pump Theory API Reciprocating Displacement Pumps Net Positive Suction Head

Net positive suction head (NSPH) is the total inlet pressure, stated in meters head minus the vapor pressure of the liquid in meters

Pump Theory API Reciprocating Displacement Pumps

What is a System ?

(in terms of the issue "NPSH")

Suction vessel p(abs)

or Habs

A system is normally composed of: · a pump · a vessel from which the pump takes the liquid (suction vessel) · piping between pump and suction vessel including valves, elbows, strainers, etc.

L

(Length of suction piping)

Hst

(Static head)

Pump

d

(pipe inside diameter)

Pump Theory API Reciprocating Displacement Pumps Mass Acceleration Forces

Simplex Pump Duplex Pump Triplex Pump Centrifugal Pump

Pump Theory API Reciprocating Displacement Pumps

Net Positive Suction Head Available NPSHA is a property of the system & determined by the purchaser! Net Positive Suction Head Required NPSHR is a property of the pump and is the minimum pressure required, measured at the suction flange, to prevent cavitation. For satisfactory pump operation NPSHA should always exceed NPSHR by a minimum of *1 -2 m

*(varies for different pump types and suppliers)

Pump Theory API Reciprocating Displacement Pumps

Total head Head of vapor pressure

The NPSH concept

Head of friction losses Head of mass acceleration losses

Head in suction vessel (above liquid level)

NPSHA

Static head

NPSHR

NPSH margin

Pump Theory API Reciprocating Displacement Pumps How can NPSHA be calculated ?

The calculation is no more than determining the difference between · positive heads i.e. absolute head in suction vessel plus static head and · negative heads (losses) i.e. head due to vapor pressure, friction and mass acceleration

NPSHA = H +Hst - Hvp - Hfr - Hma

Pump Theory API Reciprocating Displacement Pumps

Inadequate NPSHA Will Cause Cavitation Leading To: · Erratic Performance · Reduced Flow · Erosion in The Plunger Packing Area and Non Return Valves · A Lot of Noise!!! · Cost

Non Return Valves

Plunger Sealings

Pump Theory API Reciprocating Displacement Pumps

Considerations to Maximise The NPSHA of the System · Minimise the pipe length · Maximise the bore diameter · Minimise no of bend, tees and valves etc. · Use of Pulsation Dampening Devices · Increase Pressure (Booster Pump, Nitrogen Blanket, Static Head etc). · Use of a multi head pump. · Adequate Pipe Supporting

Pump Theory API Reciprocating Displacement Pumps Pulsation Dampeners

Pump Theory API Reciprocating Displacement Pumps Pulsation Dampener Affect

0

180

360

Pump Theory API Reciprocating Displacement Pumps

Overall Cost of Ownership

Comparison of the investment and maintenance costs of a hydraulically actuated diaphragm pump compared to a packed plunger pump

Process Fluid Flowrate : Methanol : 12m3/hr Process Pressure Operating Hours : 160 bar : 8000/year

Diaphragm Pump Pump Type Investment Cost Annual Spare Use - plungers - plunger packing - diaphragms - pump valves - labour costs Annual maintenance costs Maintenance costs after 3 years operation Total costs after 3 years operation Comments Energy costs Lubrication of Plunger Packing Leakage

~5% Lower Not Required None Triplex 250,000 None 3 x 500 = 1,500 3 x 1,000 = 3,000 6 x 2,000 =12,000 10 h x 150 = 1,500 18,000

Packed Plunger Pump

Triplex 150,000 6 x 3,000 = 18,000 12 x 1,000 = 12,000 None 6 x 2,000 = 12,000 50 h x 150 = 7,500 40,500

63,000 Inc 1 set of plungers 313,000

148,500

298,500

Packing Friction Necessary Needs to be contained

Pump Theory API Reciprocating Displacement Pumps

Thank you - Questions

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